KEV. A. E. EATON ON RECENT EPHEMERIDtE OR MATELIES. 81 



RHOifNANTHUS, Etn. 1881. 



Illusti'ations. Adult (details), PI. IX. 15. 



Adtdt. — Setae 2 (the median being aborted), in s twice as long as the body. Legs 

 apparently more slender than in Potamanthus ; fore tibia of 6 upwards of If as long as 

 the femur, the tarsus f as long as the tibia ; hind tarsus scarcely \ as long as the tibia- 

 Ungues unequal and dissimilar. Very like Totamantlms in other respects. 



Type. nil. speciosus, Etn. 



Distribution. Dntch East Indies. 



Etymology . port and av6og, in imitation of Potamanthus. 



Rhoenanthl's speciostjs, Etn. PI. IX. 15 ( d , wings, legs, penis, and forceps). 



Rhoenanthus speciosus, ! Etn., Eut. Mo. Mag. xvii. 192 (1881). 



Suhimago (dried). — TTings whitish, tinted more or less with very light yellowish 

 ochraceous along the inner and terminal margins ; most of the cross veinlcts between the 

 costa and anal nervure (8) of the fore wing edged with blood-red. 



Imago (dried), d . — Mesonotum brownish ochreous. Abdomen discoloured above, but 

 varied with sanguineous ; venter light yellow-oehreous. Setae whitish ochreous, their 

 joinings more or less sanguineous or atro-sanguineous ; the forceps tinged with the same 

 colour. Wings transparent ; many cross veinlets of the fore wing are conspicuously 

 bordered with sanguineous, and their bordering is irregularly confluent so as to form 

 blotches of variable extent. Legs pale ochraceous ; the fore leg at the tip of the femur, 

 at both ends of the tibia, and at the tarsal joinings, tinged with red-purple or sanguineous ; 

 hinder legs with the distal edges of the tarsal joints very narrowly sanguineous. 



2 marked similarly, but less distinctly. Length of body, d 13, 2 16; wing, d 11-12, 

 ? 16 ; setre, ? 25 & 1-26 & 1 mm. 



Hab. Lahat, Palembang, Sumatra (Mus. Soc, Zool. " Natura artis magistra " Leyden, 

 and Mus. Comp. Zool. Cambridge, Mass.). Also Java (Leyden Mus.). 



Second Series of Group) II. of the Genera. 

 Adult. — The anal (8) and normally simple second axillar (9°) nervures, with the inner 

 margin of the fore wing, enclose a trilateral space somewhat leg-of-mutton-shaped [a 

 curved trilateral, truncate at the narrow proximal end, in Ephemerella and Sageniilus'\ ; 

 anal nervure distinctly sejiarate from the pobrachial (7) at the roots ; first axillar (9') 

 usually projected in a simple curve from the prominent basal fold, and strongly arched 

 towards the inner margin ; but sometimes at the base of the wing it is curved forwards 

 abruptly, tending to annex itself to the extremity of the anal nervure, thus becoming in 

 a small degree unevenly sinuous. The area intervenient between the anal (8) and tirst 

 axillar (9') nervures is termed the " anal-axillar interspace" ; it contains from 2-5 inter- 

 polated longitudinal nervures, incurrent from the margin, termed " intercalar " or 

 " intercalary " nervures, and designated numerically in the text (but unnumbered in the 

 Plates) in the order of their nearness to the anal nervure. Hind wings of moderate or 

 small proportions, either gently, and on the whole continuously, curved in front, or else 

 suddenly refracted in the middle of the fore margin ; in the former case the subcosta (2) 



